Clinical Center healthcare workers' self-reported occupational parenteral and nonparenteral exposures to blood and other body substances were studied for two 12-month periods, one prior to, and one subsequent to, Clinical Center implementation of the final Occupational Safety and Health Administration (OSHA) bloodborne pathogens standard. These data have been used: l) to establish current levels of exposures in the Clinical Center, 2) to compare these levels of exposure with similar data obtained in previously published data, and 3) to compare results from the two 12-month periods to assess the implementation of the OSHA standard on the occurrence of occupational parenteral and nonparenteral exposures to blood and other body substances. During July 1992, selected populations of healthcare workers in the Clinical Center were invited to participate in the study. More than half of the invited participants elected to enroll. The questionnaire requested information on demographics, hepatitis B vaccination status, Universal Precautions training status, and the occurrence of parenteral, mucous membrane, and cutaneous exposures to blood and other body substances. During July 1994, a second similar questionnaire was distributed to the same selected populations of healthcare workers. These data demonstrate that most participants with occupational risk for contact with human blood or other body substances reported completion of Universal Precautions training. In 1992, study respondents reported exposure rates to blood and to all body substances, which, in comparison to previously published data collected prior to and a year following Universal Precautions training, demonstrate a continued significant decline in occupational exposures. In 1994, study respondents reported further decreased exposure rates to blood and to all body substances. The decrease in exposures associated with Universal Precautions training has persisted and decreased further since full implementation of the OSHA standard. This work is still in progress to provide further insight into the epidemiology of occupational exposures to blood and other body substances; possible prevention strategies that may further reduce the occurrence of such exposures will be investigated.